The present invention relates to cycle pedal crank assemblies.
A cycle pedal crank is known in which an open cylindrical cavity forming a crank gear box in a cycle frame contains internal threads at each end for threaded engagement with external threads on covers. The covers contain outer bearing races on their inner surfaces which cooperate with inner bearing races on a pedal crank axle to contain all bearings therebetween. Inward or outward adjustment of the threaded end covers both position the pedal crank axle and provide for required end play in the ball bearing support thereof.
This arrangement has the disadvantage that the internal threads at the ends of the cylindrical cavity are not always in alignment. This results in relative eccentricity of the inner and outer bearing races at one or both ends of the pedal crank axle thereby causing excessive wear in the bearing races and requiring additional muscular force to operate the cycle.
Furthermore, the conventional pedal crank axle and bearing is not sealed against water and dust. This further adds to excessive wear and requires periodic maintenance for cleaning and regreasing.
Further, manufacturing labor is required for machining and assembly of a pedal crank axle to a bicycle frame and for the proper adjustment of end play.